MXHR stands for multiple XmlHttpRequests and was created some days ago by digg.com front end engineers.
This awesome technology lets front end engineers request more than one resource in a single XmlHttpRequest.
As an example you will be able, in the future (the project is in alpha release), to get a javascript file, a css and some images with only one request, meaning that you will consume less bandwidth, will get data faster and it will be ordered the way you want. Cool huh?
See more detais on digg’s blog.
The aggregation is already available in Django SVN version. Now, it’s possible to do things such count authors of all book entries, count comments os all post entries, sum values of all sales to a client and much more.
Here is the official documentation of this feature: http://docs.djangoproject.com/en/dev/topics/db/aggregation/
Tags: aggregation, Django, orm
A good feature of Django Framework is the template tags and template filters. But it sucks when you have to load the filters in each template like this:
{% load mytemplatetags %}
It was much better if you just use the filters, without the need to load it. The reason you have to load is to achieve a better performance. But there’s a function of the template module called add_to_builtins that solves this problem. You can easily define a template tag or filter as builtin and use it like the builtin django template tags and filters. Just put this code in a file that is loaded ever, like the init.py of your project.
from django.template import add_to_builtins
add_to_builtins('path.to.templatetags.file')
Where ‘path.to.templatetags.file’ is the path of the file containing the template tags. For example, I have an app, inside my project, named mytagsapp. Inside this app I have the module templatetags with a file named mytags.py with my custom tags. So I will have to call add_builtins(‘mytagsapp.templatetags.mytags’). My project folder should look like this:
Folders structure
Make sure your app is in the INSTALED_APPS setting in your settings.py project. It will guarantee that the init.py of you app will get called. So just put the code above in this file (red in image).
Remember to not use this feature with all your template filters as it will mean loss of performance.
Tags: builtins, Django, Python, template filters, template tags
When you use a Model Choice Field in Django, it automatically creates an empty option in the generated select widget. But in some special cases, you don’t want this empty option to be there. So I decided to find the way to remove it. It’s much more simple then you think. Just create your model declaring the model choice field like this:
fieldname = forms.ModelChoiceField(queryset=RelationModel.objects,empty_label=None)
It’s simple like that. Just set the empty_label argument to None. But whe using ModelFormSets, there is a little more work to do. You have to create a new BaseModelFormSet like this:
from django.forms.models import BaseModelFormSet</p>
<p>class MyBaseModelFormSet(BaseModelFormSet):
def add_fields(self, form, index):
super(MyBaseModelFormSet,self).add_fields(form,index)
form.fields['fieldname'] = forms.ModelChoiceField(queryset=RelationModel.objects,empty_label=None)
Pay atention that you have to override the add_fields method and change your field in the form fields array. Finally you have to pass this BaseModelFormSet as argument to the modelformset_factory:
from django.forms.models import modelformset_factory</p>
<p>MyModelFormset = modelformset_factory(MyModel,formset=MyBaseModelFormSet)
Tags: Django, formset, Python
